Machka 

IMO, a person who wants to do cycle touring should purchase a bicycle ... any bicycle. It really doesn't matter what kind of bicycle, so long as the bicycle fits that person.

Then the person should ride the bicycle. The person should commute to and from work with the bicycle. The person should ride after work with that bicycle. The person should do longer rides on the weekend with that bicycle.

The person should pick up things like a handlebar bag, rack, trunk bag etc. to carry stuff for commuting, and stuff for the longer weekend rides.

From there, the person could pick up a few more touring-oriented items like panniers, a sleeping bag, and tent, and might try an overnight or weekend tour somewhere.

The person may discover that their bicycle choice isn't really suitable for the longer rides on weekends and weekend tours, and may then decide to purchase a bicycle more suited to such riding. The person may also discover that their initial choice of panniers etc. isn't suited to that sort of cycling either and may decide to get something better.

By doing these steps first, the person will get comfortable with riding a bicycle day after day, and will discover for themselves what works and what does not work. Trial and error. If the person follows these steps the person may end up with a collection of stuff he/she may never use again because he/she has found that something else works better, but the person will have gained experience. He/she will know what works for him/her.